hNT-Neurons are pure human neuronal cells that exhibit neuronal phenotypes and efficiently engraft following transplantation into rodent spinal cord. Phase I studies successfully developed hNT-Neurons with properties suitable for spinal cord transplantation, identified the critical experimental conditions to maximize graft success in vivo, and demonstrated graft survival in a rodent model of clinically relevant cervical spinal cord contusion injury. Phase II studies will focus on further product development, optimization of grafting protocols, and intensive anatomical, neurophysiological and behavioral studies of long-term safety and efficacy. Specific aims include: (1) examine graft survival, rate of cellular differentiation, neurotransmitter phenotypic profiles, and neuritic outgrowth as a function of the cell density of grafted hNT-Neurons; and (2) establish long-term safety and functional efficacy by monitoring the safety profile, phrenic motoneuron function, and forelimb motor behavior over extended time periods following grafts of hNT-Neurons in spinal cord contusion injury. The results of these experiments will help establish the therapeutic potential of hNT-Neurons to improve outcomes in spinal cord injury and provide valuable information necessary to move ahead toward clinical trials. PROPOSED COMMERCIAL APPLICATION: Not Available